I was on call one evening when I was asked to go to accident and emergency to see a man in his early twenties with abdominal pain. I was a junior surgeon doing my six-month stints in various surgical specialties before deciding on one, this particular one being called general surgery.

An incredibly handsome, young and fit man was waiting for me. He looked really well although he complained of a general ache in his abdomen and being constipated. When I examined him and did blood tests I couldn't find anything that looked particularly abnormal so I sent him home with some laxatives.

He came back to A&E again when I was next on call, three days later. He looked much more uncomfortable so I brought my registrar down to see him and we decided to do a CT scan to have a look at his gut.

The investigation showed that this young man had a really advanced bowel cancer, one you usually associate with people in their fifties and sixties. When you're very young your cells are incredibly active, your metabolism faster and the cancer very aggressive. We took him to the operating theatre and when we opened him up we saw the cancer in his abdomen and sigmoid colon had wrapped itself around all of his main blood vessels and had spread to the liver. You could almost see the cancer growing before your eyes.

All we were able to do was give him a stoma, which was to take a piece of his bowel and attach it to the abdominal wall so his bowel could empty into a bag.

A week of me doing night shifts coincided with the last seven days of this man's life. I used to go and see him every morning before I went home. He was very, very angry about the fact that he was going to die. They sent round psychologists to talk to him about how he needed to accept that he was dying but, understandably, he wouldn't really talk to anyone. When I visited him he didn't really talk to me, he just sat there getting sicker and sicker.

My night shifts were done and I was about to have a week off. I went to see him and just before I went he put his hand over mine.

He died a couple of hours after I left him.

It was a lesson in the limitations of what you can do as a doctor. Seeing how incredible and awful life can be. It's not a case that was difficult for me technically but it taught me that you're not going to make the slightest bit of difference a lot of the time.

Being so junior, I felt it was my job to give him some company for a few minutes, even though he never gave me any reason to think that he wanted it. He never met my eyes or communicated, except for that final gesture.

'Direct Red: A Surgeon's Story' by Gabriel Weston is out now published by Vintage